Summary says it all.
Currently, the UAC prompt when installing Libreoffice happens *way* later than it should. It doesn't occur until after the user has gone through all of install options, and the actual installation has begun.
It should be triggered as soon as the installer starts, before anything is unpacked.
Anything else is a waste of time - if the user doesn't have Admin rights, they should discover this immediately when the installer is launched, and if the user does have Admin rights, they may walk away after clicking the last 'OK' and the install begins (but before the UAC prompt occurs), and if they do, the install fails, and they have to start all over again.
I agree. This is a mistake of Microsoft not having their own guidelines (http://msdn.microsoft.com/en-us/library/windows/desktop/aa511445.aspx) in mind when developing Windows Installer. I think this can be marked as RESOLVED NOTOURBUG, unless someone develops a new, custom installer. Meanwhile, marking as NEW.
According to comment #1, closing as NotOurBug.
Best regards. JBF